Add Product
<form method="post" action="http://domain.com/mm5/merchant.mvc?Screen=BASK">
<input type="hidden" name="Action" value="ADPR">
<input type="hidden" name="Product_Code" value="Guitar_2">
<input type="text" name="Quantity" value="1" >
<input type="submit" value="Add to Cart" >
</form>